Yes, I'm thinking this Krag is definitely an American "one-off" custom job, as someone said, but it surely has a Sedgley-pattern to it.
Looked everywhere but no markings as to the 'smith's identity.
Also, I once had a "sporterized" Krag carbine that had the 1901-style rear sight - which is the one on the top left of the picture at the link Ruger450 provided. It had screws fore & aft to anchor it, but the screw holes extend into the barrel. There are no similar holes (or filled holes) on my Krag rifle where such a sight would've been, which makes me think it's either an unused 1903 barrel that was rechambered or a commercial .30cal Winchester barrel - but whichever, I don't think it's a Krag mil barrel.